totoher

Hi everyone, I'm a new Fusion Energi owner. Love the car, got 98mpg on a 50mile roundtrip just the other day on a single charge while zipping by everyone in the HOV lane. I am having an issue though, when I start getting near 70mph+ which is usually rare, there is an exhaust drone which suddenly comes up and becomes very loud. It doesn't sound like engine noise since that gets drowned out too. Was wondering if anyone else has had this issue? Thanks!